Our basement toilet won't flush during times of heavy rain. This happens about 1 or 2 days a year, usually in winter. We've learned to live with it. I have two fields - a new one installed about 4 years ago and a diverter valve - this issue happens no matter which field I'm on. As soon as it dries out, the system works fine the other 363 days a year. And this cycle has happened for the last 3 years. 3 years of 363 straight days of a normally working system tells me that my fields are fine - perhaps the situation is not ideal - yet it's just the nature of what I have.

So the ground becomes extremely saturated, the fields cannot purge off water, and the tank fills with water, as does the main line coming into my basement slab.

There is a syphoning effect happening with the basement toilet. The water in it is actually "connected" to the water in the drain, since that drain is full up to the toilet. Since those waters are touching, as the drain tries to purge, it pulls the toilet water down with it, interupting it's flush cycle. When the drain line finally dries, there's an air break and thus the toilet works normally.

Yet we continue to use water upstairs, and it does not overflow the basement toilet. I believe this is because the weight/pressure of the water upstairs (with more gravity behind it) is actually pushing/forcing the water toward the lowest drain - which is actually the septic fields, not the basement toilet or shower. I specuate that if we had no basement toilet/shower, we'd never even know we were having an issue.

So - based on everything above, is it reasonable to think that even when the fields are super-saturated, since they are lower than the whole house and every bathroom, natural water pressure from the weight of water in the house drain pipes could actually force water through the tank and squeeze it out the drain fields?

joed

01-17-2013 10:59 AM

It is a good assumption. But if the field gets saturated enough the water will overflow the toilet.

joecaption

01-17-2013 11:11 AM

There's just more empty space in the lines for the water to back up the higher you go.
Dump enough water in there and it would back up to.

jagans

01-17-2013 01:37 PM

The fact that a second leach field was installed tells me your land does not perc well at all. Is there a layer of clay involved? Was your property properly perced?

denemante

01-17-2013 02:28 PM

I have the county paperwork from when the original field was installed with the new house in 1998. Ammended to that is the plan for when the new field was installed in 2008. There is nothing on the newer plan worth much, other than it says: install per contractor and owner, divert surface water. Hi-cap serial quick 4. They did do extensive grading and installed french drains. There is a drawing of the old field and new one.

The drawing of the new field looks like a larger field than the old one.

In looking at my property, I'd say the grading and water diversion is good. All downspouts go to the corregated piping underground which goes to a runoff trench way out back. So do two french drains.

Apparently the previous owner spend a tremendous amount of money on the new field. Seems crazy that it wouldn't have been done right. I know soil is a factor. I don't know if my soil is too hard so water can't leech into it fast enough - or of it's too loose so is highly suseptible to rain water saturation. Or maybe some other problem altogether.

Since this only happens during heavy rain, maybe the tank has a leak. Maybe one of the downspot pipes or french drain runs cracked underground and is dumping water into the field vs. carrying it away. Are those thoughts more logical than thinking an expensive new field was professionally installed in ground that couldn't support it some of the time?

But for him to spend that kind of money 4 years ago, you'd think that whatever is in the new trenches might have been planned to work, not get saturated. Like better or different dirt would have been put in, better gravel/rock or however they do it.

AllanJ

01-17-2013 07:43 PM

Sometimes you can get around poor perc'ing of the soil by installing a second or a bigger drain field.

As far as French drains for other purposes improperly (or due to a defect) emptying into the septic system, you just need to investigate and find out.

To check a septic tank for performance degrading leaks, lift off one of the hatches and you need to observe the height of the liquid inside over several days with no one using water. The level (excluding the grease or scum on top) should rest about 9 inches below the top (underside of the top slab). If the level keeps dropping then you have a leak. When you use water, each gallon of new liquid coming from the house should result in a gallon of liquid exiting for the drain fields.

I have an update - I spoke with the contractor who finished the basement for the previous owner several years ago. Our septic is all gravity - no pumps. The basement bathroom was subbed, but this contractor recalled not liking it - he felt the grade leading to the tank from the basement bathroom drain wasn't enough - that may have been poor design during original construction.. Details were fuzzy, but he recalled a conversation with the previous owner about exploring a pump that would send the basement bathroom waste up where it would meet the main house drain higher up but the previous homeowner balked and apparently decided to risk it.

With this information - things begin to make sense. During rain/heavy water use, things back up and water fills the nearly flat drain pipe under my basement floor that leads to the toilet - so it can't flush. Meanwhile, the rest of the home keeps working as there is added space inside the pipes in my walls. Maybe I've been lucky, but the path of least resistance for the rest of the home waste is out towards the tank - not back towards the basement toilet. Natural weight/pressure pushes it all out to the tank. So I guess I'm lucky I have a basement toilet that works 363 days a year vs. not having one, or having one with a pump system I'd need to maintain.

All this still leaves one question - we experienced this situation a few times before the first time we had the tank pumped, and I assume the previous owner did too. When opened, the guys said the tank was exactly as it was supposed to be. And the outlet filter was clean. Some have suggested that if a tank gets 100% full and backs up, it can introduce solid waste into the fields and wreck the fields. I have a two-chambered 1000 gallon tank. It has that wall between chambers with a horizonal opening midway up that divider. The outlet side of the tank was clearly "cleanish" water, and the other side with the sludge layer/grease, etc.

So while not ideal, even when the system gets overloaded and even begins to back up into the main drain line, somehow, it's not wrecking the tank? The filter stays clean? If so - could I presume that these rarer events aren't causing damage to my fields?

Final question - the tank lids are cement and there is about 3 feet of dirt on top. But could they leak when the tank gets 100% full? Just a little seepage in the nearby ground, if anything, and no problem?

joed

01-22-2013 12:41 PM

If the level of the water in the rest of the pipes ever gets higher than the toilet rim, the toilet will over flow. The toilet must be just high enough to let the water flow out to the flooded leach field. If the wax ring at the bottom of the toilet ever goes bad the water will come out under the toilet.

denemante

01-22-2013 01:43 PM

Good point Joed - how long do those wax rings last?

Actually I have a shower in the bathroom too. Techincally it's the lowest drain in the house but a tad higher than where that wax ring sits. The washout outside is even lower. When we have this occasional issue - I'll open the washout to find it full. Yet somehow, nothing comes back into the shower drain. While not ideal, there must be enough of a grade, plus the water in the basement toilet and shower traps. It must require X amount of PSI to actually backup. What I mean is that the waste/water from the house above meets resistance from a saturated tank and decides to head back towards the basement toilet - there are natural forces fighting against that. If that PSI is less than the PSI it meets as it tries to head into the tank - then it will slowly head for the tank.

That brings me full circle to when I started this thread. Assuming the tank is 100% full and the fields are 100% saturated - and we're still using water in the house - I'm wondering if it's logical to assume - since I haven't had a backup - that my home is literally forcing water into the fields and out into the ground. Sure, it's not leaching out as it would during normal circumstances. But simply put, the path of least resistance is still out into the fields vs. back into my basement bathroom?

I'll still heed the warnings - we're not going to overload the system during these times and will be extra cautious.

BTW - the day after the rain stopped, my basement bathroom was back to 100% working order. And we had a weekend party in the basement with probably 50 more flushes than when we're home alone - no issues. So however it works, once active rain stopped and we slept overnight, that seemed to be enough time for the system to right itself.

joed

01-22-2013 02:19 PM

Sounds like the water level is just high enough to fill the pipe but not high enough back up into the shower. The filled pipe would certainly prevent the toilet from flushing.

TOOL82

01-25-2013 01:46 PM

Your drainfields are becoming completly saturated when you get real heavy rains. There is nothing wrong with your drain lines, because if there were you would have this problem when it does not rain hard. Without seeing what your property looks like I going guess the drainfield is in a low lying area or near the bottom of a slope. I would put in a swale & a curtain drain to divert the water away from the drainfield.

Your concrete access lids do leak water if they are buried 3ft. deep. I would dig them up & install Polylok risers to at least 6" above grade. This way you won't have to dig them up every time you have your tank pump which should be done every 2 - 5 years depending on useage.

Also if you are guessing you had an extra 50 flushes when you had your party that is only about 70 extra gals which should not overload a working system. Systems are usually designed to handle 150 gals. per day per bedroom. Your tank is 1,000 gals, so I guess you have a 3-4 bedroom house.

denemante

01-25-2013 02:19 PM

Out of curiousity, why do you think my two cement septic tank lids would leak, being buried 3 feet down? Do you mean rainwater might leak into them just because they aren't an airtight fit? Common sense tells me that's possible, but with dirt packed all around them, and being in an area with great runoff, I can't imagine very much water could leak in.

Or are you saying during times when my system is overloaded - sewage might be squeezed OUT?

If I put risers on and I experienced one of these overload events - I feel like the riser tubes would fill up too, then they would leak sewage now onto my lawn. Their tops would in fact be higher than my basement drain, so maybe they'd never fill up though.

As for the 50-flush party I had - yeah, that's not techincally much water use for a fully working system. What I was implying was that just a day earlier, there was standing water in my backyard, the washout was full and basement toilet unflushable. That next day, all worked perfect, as if the system was at full capacity. So even though they were saturated just a day before, my fields must have really been able to quickly purge off water and allow the system to rebalance in pretty short order.

Maintenance 6

01-25-2013 03:30 PM

Quote:

Originally Posted by denemante
(Post 1095588)

Does this make sense to you?

Our basement toilet won't flush during times of heavy rain. This happens about 1 or 2 days a year, usually in winter. We've learned to live with it. I have two fields - a new one installed about 4 years ago and a diverter valve - this issue happens no matter which field I'm on. As soon as it dries out, the system works fine the other 363 days a year. And this cycle has happened for the last 3 years. 3 years of 363 straight days of a normally working system tells me that my fields are fine - perhaps the situation is not ideal - yet it's just the nature of what I have.

So the ground becomes extremely saturated, the fields cannot purge off water, and the tank fills with water, as does the main line coming into my basement slab.

There is a syphoning effect happening with the basement toilet. The water in it is actually "connected" to the water in the drain, since that drain is full up to the toilet. Since those waters are touching, as the drain tries to purge, it pulls the toilet water down with it, interupting it's flush cycle. When the drain line finally dries, there's an air break and thus the toilet works normally.

Yet we continue to use water upstairs, and it does not overflow the basement toilet. I believe this is because the weight/pressure of the water upstairs (with more gravity behind it) is actually pushing/forcing the water toward the lowest drain - which is actually the septic fields, not the basement toilet or shower. I specuate that if we had no basement toilet/shower, we'd never even know we were having an issue.

So - based on everything above, is it reasonable to think that even when the fields are super-saturated, since they are lower than the whole house and every bathroom, natural water pressure from the weight of water in the house drain pipes could actually force water through the tank and squeeze it out the drain fields?

I'm not at all sure that this is related to your problem, and it does appear to be elevation related, but you should not have any siphoning effect going on. That tells me that the basement toilet may not be vented properly. A proper vent should break any sort of siphon action.

denemante

01-25-2013 04:43 PM

Venting has been mentioned a bunch of time - there is a studer valve for the toilet - it's in the wall behind. Before we finished off that wall, a plumber was in for other work and I had him check it - he raised it so it was up in an open ceiling void where it could get more air.

The basement toilet always "burps" once at all times when you flush it...even when we're not having issues. Like one big pre-flush bubble comes out. Our original home inspector actually noted it as a possible venting issue.

Still - that plumber checked it and the venting was "right". Apparently not.

When we have the rain events and "slow" basement toilet (or when it stops for a day) - the water is sucked right out of the toilet. So however that is happening, something is pulling it from the other side.